This Pokemon is just a floating head surrounded by smoke. It is quite similar to will-o-wisps but more specifically resembles the sogen-bi in japanese folklore. A sogen-bi is a fireball yokai that is just a man’s head surrounded by flames that flies in the sky at night.
The story of the sogenbi is that a long time ago, there was a monk named Sogen. He was a wicked monk who would steal money from the offerings to the gods. He managed to do this for years and eventually dies of old age. But because of his sins, he was then cursed to be a flying head on fire.